Top Xx Hibernate Interview Questions For Coffee J2ee Programmers

Hibernate is i of the most pop persistent frameworks inward the Java world. Hibernate offers an object to relational (ORM) solution which frees Java developers from writing tedious, hard to read too cluttered JDBC code converting SQL columns into Object properties. Apart from freeing Java developer from writing JDBC too database interaction code, Hibernate too offers the out-of-box solution on caching, proxying too lazy loading which drastically improves the surgery of your Java Web application. Given it's of import inward Java Web application evolution patch Hibernate has acquire of i of the most sought-after science too goes paw inward paw alongside Spring framework. That's why Spring too Hibernate interview questions are too real pop inward Java interviews, peculiarly for spider web evolution positions.

Earlier I stimulate got shared around Spring MVC interview questions too due to pop demand, I am similar a shot sharing some 20 oft asked Hibernate questions from diverse Java interviews.

These questions are real useful for both the telephone too the face-to-face circular of interviews too both beginners too experienced Java developers upwards to 2 to v years tin create goodness from these questions.

If yous are actively preparing for Java interviews than yous tin too banking concern check out Java Programming Interview Exposed, it non exclusively contains interview questions from Spring too Hibernate but too other of import Java topics e.g. marrow Java, information construction too algorithms, Servlet, JSP, JSF, too blueprint patterns.

Since no listing is consummate without user involvement, thence if yous stimulate got seen whatsoever expert Hibernate questions on your interviews, which is non on this listing thence experience costless to percentage alongside us.

You tin too percentage your ain questions for which yous are looking answers or yous experience it's a expert enquiry to live asked on Java JEE programming interviews.

Btw, I expression that yous stimulate got around Hibernate experience too cognition before yous locomote past times away through this listing of questions otherwise it would live quite dorsum too forth for. If yous are a beginner to Hibernate, I advise yous to outset locomote past times away through a course of written report like Spring too Hibernate for Beginners which provides all the cardinal cognition inward quick time.

After that yous tin improve sympathize the points interviewers are looking too these questions volition too brand feel to you.




20 Hibernate Questions from Java JEE Interviews

Here is my selected listing of xx Hibernate based questions for Java developers. It contains questions from Hibernate fundamentals, one-to-one, too one-to-many mappings, caching, Hibernate vs JDBC comparison, pros too cons of Hibernate, known problems alongside Hibernate, too Performance improvement.


1. What is Hibernate?
Hibernate is an ORM (Object-relational Mapping) framework, which allows the developer to concentrate on describe of piece of job organisation logic past times taking tending of the persistence of information past times itself. Java developer tin write code using object too Hibernate tin accept tending of creating those object from information loaded from the database too saving update dorsum to the database.


2. What are the advantages of Hibernate over JDBC? (detailed answer)
Apart from Persistence i.e. saving too loading information from Database, Hibernate too provides the next benefits
1) Caching
2) Lazy Loading
3) Relationship management too provides code for mapping an object to the data
4) The developer is costless from writing code to load/store information into the database.


3. Difference betwixt get() vs load() method inward Hibernate? (detailed answer)
This is i of the most oft asked Hibernate interview questions, I stimulate got seen it several times. The key departure betwixt the get() too load() method is that load() volition throw an exception if an object alongside id passed to them is non found, but get() volition render null.

Another of import departure is that charge tin render proxy without hitting the database unless required (when yous access whatsoever attribute other than id) but get() always locomote past times away to the database, thence sometimes using load() tin live faster than the get() method.

Use the load() method, if yous know the object exists, and get() method if yous are non certain almost the object's existence. See detailed answer)
The original departure betwixt save() too persist() method is that, relieve returns a Serializable object spell render type of the persist() method is void, thence it doesn't render anything.

Here is a squeamish diagram which explains the state transition inward Hibernate:

 Hibernate is i of the most pop persistent frameworks inward the Java dry reason Top xx Hibernate Interview Questions for Java J2EE Programmers



7. What is the requirement for a Java object to acquire a Hibernate entity object? (detailed answer)
It should non live lastly too must render a default, no-argument constructor. See the detailed reply to acquire to a greater extent than almost the special requirement for a Java object to acquire a Hibernate Entity.



8. What are dissimilar types of caches available inward Hibernate? (detailed answer)
This is around other mutual Hibernate interview question. Hibernate provides the out-of-box caching solution but in that place are many caches e.g. outset score cache, minute score cache, too query cache.

The outset score cache is maintained at Session score too cannot live disabled but the minute score cache is required to live configured alongside external cache provider similar EhCache.


9. What is the departure betwixt the outset too minute score cache inward Hibernate? (detailed answer)
This is i time to a greater extent than follow-up of previous Hibernate interview question. The outset score cache is maintained at Session score spell the minute score cache is maintained at a SessionFactory score too shared past times all sessions. You tin read these books to acquire to a greater extent than almost caching inward Hibernate.


10. Does Hibernate Session interface thread-safe inward Java? (detailed answer)
No, Session object is non thread-safe inward Hibernate too intended to live used with-in unmarried thread inward the application.



11. Does SessionFactory thread-safe inward Hibernate? (detailed answer)
SessionFactory is both Immutable too thread-safe too it has only i unmarried illustration inward Hibernate application. It is used to create a Session object too it too provides caching past times storing SQL queries stored past times multiple session.

The minute score cache is maintained at SessionFactory level. This tin live a hard too tricky enquiry for less experienced Java developers who are non familiar alongside thread-safety too Immutability.


12. What is dissimilar betwixt Session too SessionFactory inward Hibernate? (detailed answer)
This is around other pop Hibernate interview question, generally at a telephonic circular of interviews.

The original departure betwixt Session too SessionFactory is that the onetime is a single-threaded, short-lived object spell later on is Immutable too shared past times all Session.

It too lives until the Hibernate is running. Another departure betwixt Session too SessionFactory is that onetime provides outset score cache spell SessionFactory provides the Second score cache.


13. What is measure query inward hibernate? (detailed answer)
Criteria is a simplified API for retrieving entities past times composing Criterion objects too known equally Criterion query.

This is a real convenient approach for functionality similar "search" screens where yous tin filter information on multiple weather equally shown inward the next example:

List books = session.createCriteria(Book.class) .add(Restrictions.like("name", "java%") ) .add(Restrictions.like("published_year", "2015")) .addOrder(Order.asc("name") ) .list();
This tin live a tough enquiry if yous are non using Hibernate on a daily basis, I stimulate got interviewed several Java developers who stimulate got used Hibernate but doesn't know almost Criterion query or API. You tin banking concern check out this listing of 5 Hibernate too JPA courses for Java Programmers to acquire to a greater extent than almost JPA too Hibernate.


14. What are other ORM frameworks? Any choice of Hibernate?
This is a full general question, sometimes asked to start the conversation too other times to complete the interview. EJB too TopLink from Oracle are 2 of the most pop choice to Hibernate framework.


15. What is the departure betwixt save() too saveOrUpdate() method of Hibernate? (detailed answer)
Though both save() too saveOrUpdate() method is used to shop an object into Database, the key departure betwixt them is that relieve tin exclusively INSERT records but saveOrUpdate() tin either INSERT or UPDATE records.



16. What is departure betwixt getCurrentSession() too openSession() inward Hibernate? (detailed answer)
An interesting Hibernate interview enquiry equally yous mightiness stimulate got used both getCurrentSession() too openSession() to obtain an illustration of the Session object. I stimulate got left this enquiry unanswered for yous to reply or discovery an reply based on your experience.


17. What is Hibernate Query Language (HQL)? (detailed answer)
Hibernate query language, HQL is an object-oriented extension to SQL. It allows yous to query, store, update, too yell back objects from a database without using SQL.

This enquiry is too similar to the before enquiry almost Criterion query, Java developers who stimulate got non used Hibernate extensively volition non know much almost features similar HQL too Criterion.


18. When create yous utilisation merge() too update() inward Hibernate? (detailed answer)
This is i of the tricky Hibernate interview questions. You should utilisation update() if yous are certain that the Hibernate session does non incorporate an already persistent illustration alongside the same id too utilisation merge() if yous desire to merge your modifications at whatsoever fourth dimension without considering the state of the session. See Java Persistence alongside Hibernate for to a greater extent than details.

 Hibernate is i of the most pop persistent frameworks inward the Java dry reason Top xx Hibernate Interview Questions for Java J2EE Programmers



19. The departure betwixt sorted too ordered collection inward Hibernate? (detailed answer)
The original departure betwixt sorted too ordered collection is that sorted collection form the information inward JVM's heap retentivity using Java's collection framework sorting methods spell the ordered collection is sorted using lodge past times clause inward the database itself.

Influenza A virus subtype H5N1 sorted collection is to a greater extent than suited for pocket-size dataset but for a large dataset, it's improve to utilisation ordered collection to avoid OutOfMemoryError inward Java application.


20. How create yous log SQL queries issued past times the Hibernate framework inward Java application?
You tin utilisation the show_sql belongings to log SQL queries issued past times the Hibernate framework, Just add together the next describe inward your Hibernate configuration file:

<property name=”show_sql”> true </property>


21. What are the 3 states of a Hibernate Persistence object tin be? (detailed answer)
The Hibernate persistent or entity object tin alive inward the next 3 states:
1) transient
2) persistent
3) detached


22. What is the departure betwixt the transient, persistent too detached state inward Hibernate? (detailed answer)
New objects created inward Java plan but non associated alongside whatsoever hibernate Session are said to live inward the transient state.

On the other hand, an object which is associated alongside a Hibernate session is called Persistent object. While an object which was before associated alongside Hibernate session but currently it's non associate is known equally a detached object.

You tin telephone band save() or persist() method to shop those object into the database too convey them into the Persistent state. Similarly, yous tin re-attach a detached object to hibernate sessions past times calling either update() or saveOrUpdate() method. See Spring too Hibernate for Beginners to acquire to a greater extent than almost persistence object's lifecycle inward Hibernate.


23. Which cache is used past times Session Object inward Hibernate? First score or minute score cache? (detailed answer)
Influenza A virus subtype H5N1 Session object uses the first-level cache. As I told before the minute score cache is used at SessionFactory level. This is a expert enquiry to banking concern check if the Candidate has been working inward hibernate or not. If he has non worked inward Hibernate from a long fourth dimension thence he would acquire confused inward this question.


That's all inward this listing of Hibernate Interview enquiry for Java too JEE developers. In this article, nosotros stimulate got covered a lot of oft asked Hibernate enquiry for both beginners too experienced Java developers from all of import topics of Hibernate framework e.g. Hibernate fundamentals, caching, collection mapping, surgery tuning, mutual issues too Hibernate vs JDBC.

If yous discovery that yous lack cognition inward whatsoever especial area, I advise locomote past times away through next resources to create total those gaps inward your knowledge.

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Thanks for reading this article, if yous similar this article too interview enquiry thence delight percentage alongside your friends too colleagues. If yous stimulate got whatsoever enquiry or feedback thence delight drib a comment.

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